1. Field of the Invention
The present invention relates to anti-CD19 antibodies, particularly humanized, chimeric and human anti-CD19 antibodies, particularly monoclonal antibodies (MAbs) and fragments thereof, either naked or conjugated to at least one therapeutic and/or diagnostic agent, and methods of use thereof. In particular, the anti-CD19 antibodies can be used for treating B cell disease such as, for example, a malignancy, an inflammatory disease or disorder, or an autoimmune disease. In more particular embodiments, the anti-CD19 antibodies may comprise one or more substituted amino acids designed to optimize a physical and/or physiological characteristic of the antibody.
2. Description of Related Art
The immune system of vertebrates consists of a number of organs and cell types which have evolved to accurately recognize foreign antigens, specifically bind to, and eliminate/destroy such foreign antigens. Lymphocytes, among other cell types, are critical to the immune system. Lymphocytes are divided into two major sub-populations, T cells and B cells. Although inter-dependent, T cells are largely responsible for cell-mediated immunity and B cells are largely responsible for antibody production (humoral immunity).
In humans, each B cell can produce an enormous number of antibody molecules. Such antibody production typically ceases (or substantially decreases) when a foreign antigen has been neutralized. Occasionally, however, proliferation of a particular B cell will continue unabated and may result in a cancer known as a B cell lymphoma or leukemia. B-cell lymphomas, such as the B-cell subtype of non-Hodgkin's lymphoma, are significant contributors to cancer mortality.
The response of B-cell malignancies to various forms of treatment is mixed. For example, in cases in which adequate clinical staging of non-Hodgkin's lymphoma is possible, field radiation therapy can provide satisfactory treatment. Still, about one-half of the patients die from the disease. Devesa et al., J. Nat'l Cancer Inst. 79:701 (1987).
The majority of chronic lymphocytic leukemias are of the B-cell lineage. Freedman, Hematol. Oncol. Clin. North Am. 4:405 (1990). This type of B-cell malignancy is the most common leukemia in the Western world. Goodman et al., Leukemia and Lymphoma 22: 1 (1996). The natural history of chronic lymphocytic leukemia falls into several phases. In the early phase, chronic lymphocytic leukemia is an indolent disease, characterized by the accumulation of small mature functionally-incompetent malignant B-cells having a lengthened life span. Eventually, the doubling time of the malignant B-cells decreases and patients become increasingly symptomatic. While treatment can provide symptomatic relief, the overall survival of the patients is only minimally affected. The late stages of chronic lymphocytic leukemia are characterized by significant anemia and/or thrombocytopenia. At this point, the median survival is less than two years. Foon et al., Annals Int. Medicine 113:525 (1990). Due to the very low rate of cellular proliferation, chronic lymphocytic leukemia is resistant to cytotoxic drug treatment. Traditional methods of treating B-cell malignancies, including chemotherapy and radiotherapy, have limited utility due to toxic side effects.
B cells comprise cell surface proteins which can be utilized as markers for differentiation and identification. One such human B-cell marker is a CD19 antigen and is found on mature B cells but not on plasma cells. CD19 is expressed during early pre-B cell development and remains until plasma cell differentiation. CD19 is expressed on both normal B cells and malignant B cells whose abnormal growth can lead to B-cell lymphomas. For example, CD19 is expressed on B-cell lineage malignancies, including, but not limited to non-Hodgkin's lymphoma, chronic lymphocytic leukemia, and acute lymphoblastic leukemia.
A potential problem with using non-human monoclonal antibodies (e.g., murine monoclonal antibodies) is typically lack of human effector functionality. In other words, such antibodies may be unable to mediate complement-dependent lysis or lyse human target cells through antibody-dependent cellular toxicity or Fc-receptor mediated phagocytosis. Furthermore, non-human monoclonal antibodies can be recognized by the human host as a foreign protein and, therefore, repeated injections of such foreign antibodies can lead to the induction of immune responses leading to harmful hypersensitivity reactions. For murine-based monoclonal antibodies, this is often referred to as a Human Anti-Mouse Antibody (HAMA) response.
The use of chimeric antibodies is more preferred because they do not elicit as strong a HAMA response as murine antibodies. Chimeric antibodies are antibodies which comprise portions from two or more different species. For example, Liu, A. Y. et al, “Production of a Mouse-Human Chimeric Monoclonal Antibody to CD20 with Potent Fc-Dependent Biologic Activity” J. Immun. 139/10:3521-3526 (1987), describe a mouse/human chimeric antibody directed against the CD20 antigen. See also, PCT Publication No. WO 88/04936. However, no information is provided as to the ability, efficacy or practicality of using such chimeric antibodies for the treatment of B cell disorders in the reference. It is noted that in vitro functional assays (e.g., complement-dependent lysis (CDC); antibody dependent cellular cytotoxicity (ADCC), etc.) cannot inherently predict the in vivo capability of a chimeric antibody to destroy or deplete target cells expressing the specific antigen. See, for example, Robinson, R. D. et al., “Chimeric mouse-human anti-carcinoma antibodies that mediate different anti-tumor cell biological activities,” Hum. Antibod. Hybridomas 2:84-93 (1991) (chimeric mouse-human antibody having undetectable ADCC activity). Therefore, the potential therapeutic efficacy of a chimeric antibody can only truly be assessed by in vivo experimentation, preferably in the species of interest for the specific therapy.
One approach that has improved the ability of murine monoclonal antibodies to be effective in the treatment of B-cell disorders has been to conjugate a radioactive label or chemotherapeutic agent to the antibody, such that the label or agent is localized at the tumor site. For example, studies indicate that 90Y labeled anti-CD19 antibodies can be used to reduce lymphoma in mice (McDevitt et al., Leukemia 16:60, 2002), anti-CD19 antibodies conjugated to idarubicin result in tumor regression in an experimental model (Rowland et al., Cancer Immunol. Immunother., 37:195, 1993), and 125I and 111In radiolabeled anti-CD19 is specifically taken up in tumor bearing organs (Mitchell et al., J. Nucl. Med., 44: 1105, 2003). Combination therapy with an anti-CD19 antibody is also disclosed in Ek et al., Leuk. Lymphoma 31: 143 (1998) and Uckun et al., Blood, 79:3116 (1992). Treatment of human B cell lymphoma with an anti-CD19 antibody and anti-CD3 x anti-CD19 diabody is disclosed in Hekman et al., Cancer Immunol. Immunother., 32:364 (1991) and Cochlovius et al., J. Immunol., 165:888 (2000), respectively.
However, these approaches have not eliminated the obstacles associated with using murine antibodies, despite the fact that many patients with lymphoma who have received prior aggressive cytotoxic chemotherapy are immune suppressed, thus having lower HAMA rates than lymphoma patients who have not been heavily pretreated.
Inflammatory diseases, including autoimmune diseases are also a class of diseases associated with B-cell disorders. The most common treatments are corticosteroids and cytotoxic drugs, which can be very toxic. These drugs also suppress the entire immune system, can result in serious infection, and have adverse affects on the bone marrow, liver and kidneys. Other therapeutics that have been used to treat Class III autoimmune diseases have been directed against T-cells and macrophages. There is a need for more effective methods of treating autoimmune diseases, particularly Class III autoimmune diseases.